The present disclosure relates generally to verifying operation of a remotely mounted contactor type switch that can be safely measured to be closed by a measurement system connected over a wire. An exemplary system includes a flame scanner with an internal relay connected to a burner management system that detects when the flame scanner relay contact has closed, thereby indicating the presence of a flame. If a flame is not detected, then the flame relay is open.
It is known in the art to test the flame relay circuitry to confirm proper operation. It is desirable to determine if the flame relay is closed or if a short circuit has occurred across the flame relay, which results in a false indication of flame presence. Existing designs place a known resistance in series with the flame relay and apply a static current across the resistor when the relay is closed. If the proper resistance is measured by the static current, this indicates that the flame relay is closed. However, determining the closure of the flame relay by measuring the resistance with a static current or voltage does not allow for a fail-safe system for all known failure modes. Numerous other component failures in the system may falsely indicate a closed flame relay in a static system (e.g., leakage voltage on a detection circuit board, crosstalk on wiring to/from the flame relay, a damaged A/D converter, faulty drive current, etc.). A more thorough detection of proper contact operation via dynamic drive current would be well received in the art.